Status Report

Ed Lu’s Journal: Entry #7: Working Out

By SpaceRef Editor

July 29, 2003

Filed under Ed Lu's Journal, ISS, Johnson Space Center, US

Ed Lu’s Journal: Entry #7: Working Out — ed lu

Today,
like everyday, I had two scheduled exercise sessions. That’s
because exercise up here is even more important than it is
on the ground. On the ground you get a lot of exercise without
even knowing it because your body is constantly working against
the force of gravity. Your muscles and bones have to support
your own body weight all day long. Up here, as far as your
muscles and bones are concerned, life is just effortless.
Since we hardly have to exert any effort to get around in
space, we have to maintain our fitness levels by working out
twice a day. Our trainers on the ground, Jamie and Beth, design
my space workout program and keep track of my progress.

Besides
just our aerobic fitness levels, we also have to deal with
about bone and muscle loss. I remember back when I had a major
knee operation many years ago and basically didn’t use my
leg muscles for a few weeks while I was in a cast. When they
took the cast off, my right leg was about half the size of
my left leg. It was amazing how fast the muscles had atrophied.
The same process of muscle loss occurs in space if the muscles
aren’t being used, and is one of the big medical challenges
associated with long-term space flight. Astronauts also lose
bone density in the major weight bearing bones (hips, lower
back, femur, etc.) during long-duration space flights. This
loss of bone density is similar to the bone loss that often
occurs in the elderly (osteoporosis), and is one of the reasons
many older adults suffer broken bones in falls. The reasons
for the bone loss in weightlessness (or due to advancing age
for that matter) aren’t totally clear, but we do know that
it has something to do with the fact that your body is constantly
rebuilding your bones, and that this process is affected by
how much mechanical load is carried by the bones. If you are
looking for something to do, figure out how bears and other
animals that hibernate manage to not lose bone and muscle
strength even though they don’t move for months, then figure
out how to make it work for humans. You’ll be a hero!

These
are problems that must be overcome when we eventually (hopefully,
in the not too distant future) take long voyages around our
solar system such as to Mars or to asteroids. When landing
on Mars, the astronauts will need to be ready to start work
immediately after reaching the surface of the planet and will
not have time for months of rehabilitation. Luckily, the solution
to the problem in space is the same as it is on Earth, namely
exercise. We have some indications that we may be close to
solving the problem. In fact, one of our main goals this mission
is to see if we can replicate the very good results obtained
by some previous ISS crew members in preventing bone and muscle
loss. If that wasn’t enough motivation, I made a bet with
Peggy Whitson (Expedition 5 astronaut) that I would beat her
bone density loss measurements! The motivating factor isn’t
so much the one dollar we have riding on it, it is knowing
that Peggy will never ever let me forget it if I come back
with greater bone loss than her (not that I don’t have similar
plans if I win the bet!).

We rotate
our workouts through four main pieces of exercise equipment
on ISS: a treadmill, 2 stationary bikes, and an apparatus
that allows you to “lift weights.” The treadmill
is a 900-pound monster that resides in the Service Module
(unfortunately right next to our dinner table). The treadmill
is so big because it isn’t bolted to the floor, but rather
is loosely suspended inside a pit in the floor and has a big
gyroscope inside that stabilizes it while you run. This is
to isolate the vibrations from your footsteps so they don’t
shake the Station around. In effect, you are running on a
floating treadmill. It might seem strange to think that a
person running could shake a 200-ton Space Station, but in
fact it can. On my first space mission we visited the Russian
Mir Space Station, and I remember watching a crew member run
on the treadmill there (which was hard-mounted to the floor).
As they ran, you could feel the oscillations reverberate through
the Mir, and in fact you could actually look outside and see
the big solar arrays actually move up and down. For those
of you who know what resonant frequencies are, that was what
was going on. To prevent this, the elaborate treadmill system
was developed and is used on ISS. It is kind of interesting
running on the treadmill because the “floor” underneath
your feet moves around a bit, like running on the deck of
a small boat.

You might
be wondering how we can actually run since we are weightless
– the answer is we wear a harness (that fits like a backpack
harness) that is connected to the treadmill with bungee straps.
There is, however, an important difference between running
here while being strapped to the treadmill and running on
Earth. If you load up the bungees so they pull down with a
force equal to your body weight, all that force is transferred
by the harness to the contact points on your shoulders and
hips, which can get pretty sore after running for a while.
The fit of the harness depends on your body shape, and I’ve
been trying various adjustments of the straps to improve the
fit while the engineers on the ground work on a better design.
The main purpose to the treadmill, of course, is to work out
those walking and running muscles that would otherwise go
unused up here. To get a good aerobic workout, I walk for
a mile, then run a couple of sets of half a mile each, then
walk for a while longer. The pounding from the running may
be helpful for preventing bone loss in the hips and legs,
although the astronauts who flew on the Mir Space Station
ran on the treadmill there and still suffered significant
bone loss. In any case, I do four workouts a week on the treadmill.

We also
have two stationary bicycles, one American built located in
the Laboratory Module, and a Russian built version located
in the Service Module. The riding motion is a little different
than what you might have in a gym on the ground since you
don’t actually sit on a seat. The great part about the bicycles
is that they are mounted facing the two largest windows on
the Space Station, so while you ride the bike you can look
out the window and watch the world go by. If you ride the
bike for 90 minutes, you can ride all the way around the world
– so Lance Armstrong eat your heart out! I ride the bike four
times a week, and do a variety of workouts from intervals
with bursts at high resistance, to longer workouts at lower
resistance. We have a heart rate monitor that records your
pulse, and I send the data down to the ground so Jamie and
Beth can see that I’m not slacking off. The bike is mainly
for aerobic exercise, and in fact we measure our aerobic fitness
each month by riding a set resistance profile while wearing
heart and blood pressure sensors. My first fitness evaluation
was after being up here for just two weeks, and it showed
about a 20 percent decrease from my pre-flight level, which
was pretty typical. At that point your body is still getting
used to weightlessness, and the first week is typically so
busy you don’t have much time to exercise. Since then it has
improved steadily so that now I’m almost recovered to my pre-flight
fitness level.

The piece
of equipment that I use the most goes by the acronym RED (resistive
exercise device), which is our version of lifting weights.
It is two canisters, each about the size of a watermelon,
that are bolted to an aluminum plate. Inside each canister
is a cord that wraps around a spiral pulley that unwinds as
you pull the cord out. The resistance is provided by a stacked
series of disks with rubber spokes inside the canister connected
to the spiral pulley. The whole assembly inside the canister
winds up like a rubber band-powered toy as you pull the cord.
You choose the resistance level by turning a crank that winds
the disks in the opposite direction. The canisters can be
loaded up to about 120 pounds on a side. You can also add
some bungees to increase the resistance of each can to about
190 pounds, so the maximum “weight” you can exercise
with is about 380 pounds. We have a bunch of attachments like
bars and harnesses that connect to the cords so you can do
various exercises. This is the device that seems to make the
most difference with respect to overall strength and reducing
bone loss. The idea here is to workout at near maximum strength
using the major weight bearing muscle groups (hips, lower
back, and legs). The concept is familiar to athletes and weightlifters
in particular – if you want to get stronger, or at least not
lose strength, then you need to have some workouts at near
maximum effort. I use the RED six times a week, with workouts
consisting of squats, single leg squats, dead lifts, heel
raises, bench press, upright rows, abdominal crunches, and
leg extensions. I also do some exercises that are familiar
to wrestlers, namely holding a position similar to a good
wrestling stance for several minutes, which works out the
thighs and hips. All those years of drilling takedowns have
paid off! An interesting side note is that amongst the astronaut
corps, I know of at least 12 who were former wrestlers, and
seven of us competed at the collegiate level. Of those, five
of us were actually high school wrestling coaches before we
became astronauts. There are also a number of cosmonauts who
are ex-wrestlers. So it seems if you want to become an astronaut,
wrestling is a good sport to be involved in!

We’ll
see how I fare after the mission when they measure our fitness
level, strength, and bone density. If indeed we are able to
control, or at least greatly reduce the amount of degradation,
then we may be on our way to solving one of the big medical
problems with going to Mars.

Running
on the treadmill: the entire treadmill below my feet is floating
in a big pit in the floor.